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Abstract
The solubility of natural 7Be from air particulate matter in seawater was determined as a function of time. Adsorption of the thus solubilized 7Be on a variety of substrates was investigated. 7Be appears to be strongly adsorbed on suspended matter and inorganic materials at high suspended loads (> 20 mg 1−1), but at natural levels (∼1 mg 1−1) is only partially adsorbed. Further, at natural concentrations of suspended matter, adsorption of 7Be appears to be directly proportional to suspended load. Because a non-steady-state flux of 7Be to the bottom could be expected over its 53-day half-life, 7Be may be a poor tracer of sedimentation rates and sediment redistribution processes.
... Given the typical pH range of natural waters of 5-9, equilibrium-based thermodynamic models would predict that the relative Be species abundances and the partitioning of cosmogenic Be may vary by orders of magnitude between slightly acidic systems and more alkaline systems. Indeed, experimental studies demonstrate that the partitioning of Be from the aqueous phase to an adsorbed phase on a range of materials is strongly pH dependent (Bloom and Crecelius 1983;Hawley et al. 1986;You et al. 1989). Using 3-week equilibration periods, You et al. (1989) showed a >100-fold variation in the solid-phase partitioning coefficient (K d in kg L À1 ) over the pH range of 4-8 for different substrate types ( Fig. 5.3). ...
... In freshwater rivers, amounts of dissolved 7 Be in the water column are commonly below detection limits (Dominik et al. 1987;Bonniwell et al. 1999), but in marine environments, Be may be characterized as having a limited affinity for suspended matter, as large fraction of the 7 Be and 10 Be appears to be dissolved (Merrill et al. 1960;Bloom and Crecelius 1983;Kusakabe et al. 1987;Dibb and Rice 1989a;Measures et al. 1996). The mechanism of Be adsorption onto inorganic minerals, including primary silicate minerals, secondary silicates, and iron and aluminum oxyhydroxides is typically considered to be via the formation of a complex between the Be atom and oxygen on 10 Be concentration (atoms g -1 ) ...
... Like other particlereactive metals, the K d varies inversely with suspended solids concentrations below 30 mg L À1 (Hawley et al. 1986). While Be can form complexes with organic matter functional groups (daSilva et al. 1996), its partitioning coefficients seem to be significantly higher for inorganic materials compared with algae or seston (Bloom and Crecelius 1983;Dibb and Rice 1989a). Selective chemical extractions of marine sediments (Bourles et al. 1989) and soils (Barg et al. 1997) show that most of the meteoric Be is associated with authigenic phases (secondary Al, Fe, and Mn minerals) and organic matter coatings. ...
... Given the typical pH range of natural waters of 5-9, equilibrium-based thermodynamic models would predict that the relative Be species abundances and the partitioning of cosmogenic Be may vary by orders of magnitude between slightly acidic systems and more alkaline systems. Indeed, experimental studies demonstrate that the partitioning of Be from the aqueous phase to an adsorbed phase on a range of materials is strongly pH dependent (Bloom and Crecelius 1983;Hawley et al. 1986;You et al. 1989). Using 3-week equilibration periods, You et al. (1989) showed a >100-fold variation in the solid-phase partitioning coefficient (K d in kg L À1 ) over the pH range of 4-8 for different substrate types ( Fig. 5.3). ...
... In freshwater rivers, amounts of dissolved 7 Be in the water column are commonly below detection limits (Dominik et al. 1987;Bonniwell et al. 1999), but in marine environments, Be may be characterized as having a limited affinity for suspended matter, as large fraction of the 7 Be and 10 Be appears to be dissolved (Merrill et al. 1960;Bloom and Crecelius 1983;Kusakabe et al. 1987;Dibb and Rice 1989a;Measures et al. 1996). The mechanism of Be adsorption onto inorganic minerals, including primary silicate minerals, secondary silicates, and iron and aluminum oxyhydroxides is typically considered to be via the formation of a complex between the Be atom and oxygen on 10 Be concentration (atoms g -1 ) ...
... Like other particlereactive metals, the K d varies inversely with suspended solids concentrations below 30 mg L À1 (Hawley et al. 1986). While Be can form complexes with organic matter functional groups (daSilva et al. 1996), its partitioning coefficients seem to be significantly higher for inorganic materials compared with algae or seston (Bloom and Crecelius 1983;Dibb and Rice 1989a). Selective chemical extractions of marine sediments (Bourles et al. 1989) and soils (Barg et al. 1997) show that most of the meteoric Be is associated with authigenic phases (secondary Al, Fe, and Mn minerals) and organic matter coatings. ...
7Be (T1/2 = 53 days) and 10Be (T1/2 = 1.4 Ma) form via natural cosmogenic reactions in the atmosphere and are delivered to Earth’s surface by wet and dry deposition.
The distinct source term and near-constant fallout of these radionuclides onto soils, vegetation, waters, ice, and sediments
makes them valuable tracers of a wide range of environmental processes operating over timescales from weeks to millions of
years. Beryllium tends to form strong bonds with oxygen atoms, so 7Be and 10Be adsorb rapidly to organic and inorganic solid phases in the terrestrial and marine environment. Thus, cosmogenic isotopes
of beryllium can be used to quantify surface age, sediment source, mixing rates, and particle residence and transit times
in soils, streams, lakes, and the oceans. A number of caveats exist, however, for the general application of these radionuclides
as tracers in the environment, as steady deposition and geochemical immobility are not guaranteed in all systems. Here we
synthesize and review scientific literature documenting the deposition and behavior of these nuclides at the Earth’s surface,
focusing on current and potential applications for Earth scientists working to quantify terrestrial and marine processes.
... Partitioning of Be in natural waters is largely a function of suspended-sediment concentration, particulate composition, and salinity (Bloom and Crecelius, 1983; Hawley et al., 1986; Olsen et al. 1986; Dibb and Rice, 1989; Baskaran and Santschi, 1993; Baskaran et al., 1997). Laboratory and field studies have shown that the particle-adsorbed fraction of radionuclides Th, Be, and Pb in shallow-marine waters increases with increasing suspended-sediment concentration, due to a larger number of sorption sites (Santschi et al., 1979; Bloom and Crecelius, 1983; Baskaran and Santschi, 1993). ...
... Partitioning of Be in natural waters is largely a function of suspended-sediment concentration, particulate composition, and salinity (Bloom and Crecelius, 1983; Hawley et al., 1986; Olsen et al. 1986; Dibb and Rice, 1989; Baskaran and Santschi, 1993; Baskaran et al., 1997). Laboratory and field studies have shown that the particle-adsorbed fraction of radionuclides Th, Be, and Pb in shallow-marine waters increases with increasing suspended-sediment concentration, due to a larger number of sorption sites (Santschi et al., 1979; Bloom and Crecelius, 1983; Baskaran and Santschi, 1993). Hence, in particle-rich estuarine and shelf waters, a large fraction of total Be is associated with the particulate phase (e.g., Olsen et al., 1986; Dibb and Rice, 1989; Baskaran and Santschi, 1993). ...
... In contrast, the distribution of Be in particle-deficient oceanic waters are largely a function of latitudinal precipitation patterns and mixing within the surface layer (Silker, 1972; Young and Silker, 1980; Kadko and Olson, 1996). Partitioning of Be in natural waters is largely a function of suspended-sediment concentration, particulate composition, and salinity (Bloom and Crecelius, 1983; Hawley et al., 1986; Olsen et al. 1986; Dibb and Rice, 1989; Baskaran et al., 1997). Laboratory and field studies have shown that the particle-adsorbed fraction of radionuclides Th, Be, and Pb in shallow-marine waters increases with increasing suspended-sediment concentration, due to a larger number of sorption sites (Santschi et al., 1979; Bloom and Crecelius, 1983;). ...
Sediment inventories of the cosmogenic radionuclide Be (t "53 d) were measured on the Eel River shelf and slope (northern California continental margin) to investigate sedimentation processes associated with coastal river flooding. Seabed coring shortly after major riverflow events in 1995 and 1997 documented a shelf-wide flood deposit, and subsequent radionuclide studies determined Be to be a powerful tracer of fine-grained river sediment. In addition, distinctive signatures of Th and Pb were observed in oceanic flood deposits and provided additional information regarding depositional processes. During the 1995—1997 monitoring period, Be was present (2—35 dpm cm\) in shelf and slope sediments only after periods of high rainfall and river runoff during the winter months. It is suggested that fluvial input was the primary source of Be in shelf sediments after the floods. Be sediment inventories and sediment-trap fluxes determined after the 1997 flood revealed that fine-grained fluvial sediments were rapidly (within one month) broadcast over the continental margin, to the 500 m isobath. Dispersal was apparently facilitated by energetic storm waves, which resuspended and redis-tributed some fraction of the suspended load residing on the shelf prior to accretion as flood deposits. These observations illustrate that floods are an important sedimentary process for modern environments of the Eel shelf and slope, and perhaps for other fluviomarine sedimen-tary systems of the northern California continental margin. Ratios of the Pb sediment-accumulation rate (100 yr average) to the Be deposition rate (1—2 month average) for shelf sites illustrate the episodic nature of shelf sedimentation, and suggest that a minimum of 3—30 depositional events complete the most recent stratigraphic record. This observation is consis-tent with the magnitude and frequency of fluvial sediment input, as Eel River floods with return periods of 3—33 yr (3% of the time of record) have supplied '80% of the total 85 yr suspended load. Based on radionuclide and hydrologic data, it can be concluded that a small number of flood depositional events have had a disproportionate impact on the sedimentary record of the Eel shelf.
... The dissolved phase of 7 Be in water was analyzed. Bloom and Crecelius (1983) reported that the solubility of 7 Be 2+ from submicron aerosols of air in seawater was a function of time and that 7 Be appeared to be strongly adsorbed on suspended matter and inorganic material at high suspended loads (N20 mg L −1 ) and was only partially adsorbed at natural levels (~1 mg L −1 ). Hawley et al. (1986) reported that the partitioning coefficient (K d ) of 7 Be in fresh water varied inversely with the solids concentrations at typical environmental values (up to 30 mg L −1 ). ...
... However, the 7 Be mass activity in sediment from the bare plot was lower or higher than in the upper 6 mm of soil, which indicated that small rill erosion occurred in the bare plot for some erosive rainfall events. Compared with the previous results (Bloom and Crecelius 1983;Hawley et al. 1986;Matisoff et al., 2002;Olsen et al. 1986), the 7 Be activity in runoff in this study was higher and varied slightly. The main reason was that the clear runoff without filtering was used after settling for N24 h. ...
Beryllium-7 (7Be), as a potentially powerful tracer, was widely used to document soil redistribution and identify sediment sources in recent decades, but the quantity and distribution of 7Be in vegetation, soil, sediment and runoff on the Loess Plateau have not been fully described. In this study, we measured 7Be in vegetation, soil, sediment and runoff on the northern Loess Plateau of China and analyzed its variations during the rainy season to assess the potential of the 7Be method for documenting soil redistribution and identifying sediment sources in a wide range of environments. The results indicated that vegetation, soil, and sediment samples showed higher levels and larger variations of 7Be activities during the rainy season. The drying plants showed 7Be mass activity that was more than three times higher than that of living and semi-decomposed plants. 7Be mass activity in plants and sediment was much higher than in the soil. 7Be activity in runoff water with a few submicron suspended particles varied slightly and was far lower than in plant, soil and sediment samples. The cumulative precipitation generally determined 7Be inventory held by plants and soil. An inverse relationship was found between the 7Be mass activity in sediment and the sediment amount. Globally, approximate 30% of the total 7Be was held by plants in both the herbaceous and subshrub plots. Approximate 10% of the total 7Be was lost with sediment from the bare plot. A very small proportion of 7Be (1.18%-3.20%) was lost with runoff, and the vast majority of 7Be was retained in the slope soil at the end of rainy season. Vegetation cover and soil erosion significantly affected the spatial distribution and variations of the 7Be inventory in soil, providing a necessary condition for the development of a 7Be method to document soil erosion on slopes with vegetation.
... 7 Be, a short-lived radioactive nuclide (T 1/2 = 53 day), is a powerful tool for examination of environmental processes (Olsen et al., 1985). It can provide information on diffusion processes of the ocean layer, but it a poor tracer of sedimentation rates in natural environments due to its short half-life of 53 days (Bloom and Crecelius, 1983). Mixing by physical or biological activities alter the rate of dissolution of minerals and can speed up reactions (Henderson et al., 1999). ...
... Two sediment cores from the coastal Red Sea in close proximity to Jeddah were analyzed for radionuclide activities (Fig. 1). 7 Be is known to be soluble in marine environments (Bloom and Crecelius, 1983) and this increase in solubility would be exacerbated in a high saline environment such as the Red Sea. In this study, we used 7 Be as a tracer of rapid chemical diffusion to track chemical diffusion in marine sediments. ...
The Red Sea is a unique ecosystem with high biodiversity in one of the warmest regions of the world. In the last five decades, Red Sea coastal development has rapidly increased. Sediments from continental margins are delivered to depths by advection and diffusion-like processes which are difficult to quantify yet provide invaluable data to researchers. Beryllium-7, lead-210 and ceseium-137 were analyzed from sediment cores from the near-coast Red Sea near Jeddah, Saudi Arabia. The results of this work are the first estimates of diffusion, mixing, and sedimentation rates of the Red Sea coastal sediments. Maximum chemical diffusion and particle mixing rates range from 69.1 to 380 cm− 2 y− 1 and 2.54 to 6.80 cm− 2 y− 1, respectively. Sedimentation rate is constrained to approximately 0.6 cm/yr via multiple methods. These data provide baselines for tracking changes in various environmental problems including erosion, marine benthic ecosystem silting, and particle-bound contaminant delivery to the seafloor.
... Here, our solubility index showed higher solubility of 7 Be than 210 Pb in precipitation. It has likewise been shown that 7 Be in PM2.5 is almost entirely soluble in water (Bloom andCrecelius 1983, Bondietti et al. 1988). The solubility of 7 Be in PM10 is similarly high with an average of 81% removed in deionized water, but only 28% of 210 Pb (Landis et al. in review). ...
... Beryllium is a particle-reactive element and can be scavenged from seawater, for example, in the coastal ocean. However, earlier work (Bloom & Crecelius, 1983;Merrill et al., 1960;Silker, 1972;Silker et al., 1968) found that particulate 7 Be activities in the open ocean are typically <10% of the total 7 Be inventory (Silker, 1972;Kadko & Prospero, 2011). Indeed, Kadko and Prospero (2011) found good agreement between the independently measured atmospheric flux of 7 Be and water column inventories. ...
Deposition of aerosols to the surface ocean is an important factor affecting primary production in the surface ocean. However, the sources and fluxes of aerosols and associated trace elements remain poorly defined. Aerosol ²¹⁰Pb, ²¹⁰Po, and ⁷Be data were collected on US GEOTRACES cruise GP15 (Pacific Meridional Transect, 152°W; 2018). ²¹⁰Pb fluxes are low close to the Alaskan margin, increase to a maximum at ∼43°N, then decrease to lower values. There is good agreement between ²¹⁰Pb fluxes and long‐term land‐based fluxes during the SEAREX program (1970–1980s), as well as between GP15 and GP16 (East Pacific Zonal Transect, 12°S; 2013) at adjacent stations. A normalized fraction f(⁷Be, ²¹⁰Pb) is used to discern aerosols with upper (high f) versus lower (low f) troposphere sources. Alaskan/North Pacific aerosols show significant continental influence while equatorial/South Pacific aerosols are supplied to the marine boundary layer from the upper troposphere. Lithogenic trace elements Al and Ti show inverse correlations with f(⁷Be, ²¹⁰Pb), supporting a continental boundary layer provenance while anthropogenic Pb shows no clear relationship with f(⁷Be, ²¹⁰Pb). All but four samples have ²¹⁰Po/²¹⁰Pb activity ratios <0.2 suggesting short aerosol residence time. Among the four samples (²¹⁰Po/²¹⁰Pb = 0.42–0.88), two suggest an upper troposphere source and longer aerosol residence time while the remaining two cannot be explained by long aerosol residence time nor a significant component of dust. We hypothesize that enrichments of ²¹⁰Po in them are linked to Po enrichments in the sea surface microlayer, possibly through Po speciation as a dissolved organic or dimethyl polonide species.
... Here, our solubility index showed higher solubility of 7 Be than 210 Pb in precipitation. It has likewise been shown that 7 Be in PM2.5 is almost entirely soluble in water (Bloom & Crecelius, 1983;Bondietti et al., 1988). The solubility of 7 Be in PM10 is similarly high with an average of 81% removed in deionized water, but only 28% of 210 Pb (Landis et al., 2021). ...
We report fallout radionuclide (FRN) and major/trace element (MTE) contributions to bulk atmospheric deposition in Hanover, NH, USA (43.7022°N, 72.2896°W). Deposition of ⁷Be, ²¹⁰Pb, and SO4 covary [R² > 0.4, n = 461] but are discriminated by production sources, depositional mechanisms, meteorological controls, MTE associations, and seasonal biases. ⁷Be is dominated by rainout (78% of total deposition), recharged by long‐range transport (+23% over mean, o.m.), influenced by stratosphere‐troposphere exchange (+9% o.m.), and solar activity (−2% per doubling of sunspot count). Correlation with particulate nitrogen (+9% per doubling of N) indicates ⁷Be affinity for biogenic aerosols. ²¹⁰Pb is dominated by dry + washout deposition (54% of total) and convective storms (+107% o.m), depleted in marine moisture sources (−133% o.m.), correlated with S (+9% per doubling of S), and biased to autumn with Mn, Hg, and V (+7% o.m.). Coincident long‐term declines in S and ²¹⁰Pb (−14%, −4% per year) suggest co‐scavenging by PbSO4. ⁷Be:²¹⁰Pb ratios increase asymptotically with precipitation through the dry‐washout‐rainout transition and recharge of ⁷Be. At the global scale, ⁷Be:²¹⁰Pb increases with precipitation for North American/European sites due to recharge of ⁷Be in midlatitude storm belts [R² = 0.64, n = 31]. Conversely, ⁷Be:²¹⁰Pb is independent of precipitation for Southeast/East Asian sites where ⁷Be recharge is low [R² = 0.01, n = 40]. Globally, ⁷Be:²¹⁰Pb ratios in dry deposition reflect resuspended aerosols with mean age of ca. 200 days, contributing <5% of ²¹⁰Pb deposition. Different aerosol populations contributing to FRN deposition across spatial and temporal scales should emerge as a focus in terrestrial ⁷Be, ²¹⁰Pb, and ¹⁰Be tracer applications.
... The K d values obtained for the layer below the thermocline were comparable with those of SML and averaged (1.8 ± 0.2) × 10 2 and (1.6 ± 0.2) × 10 2 m 3 kg − 1 , respectively. According to previously published data, K d for 7 Ве in seawater varies widely and constitutes (3-8) × 10 2 m 3 kg − 1 in Sequim Bay, Pacific Ocean (Bloom and Crecelius, 1983), (0.9-11) × 10 2 m 3 kg − 1 in Pacific and Southern Oceans (Chase et al., 2002), (0.01-9.5) × 10 2 m 3 kg − 1 in the Gulf of Mexico, Atlantic Ocean (Yang et al., 2015). ...
Spatial variability of ⁷Be activity in both particulate and dissolved phases in the Black Sea was studied using field observations from the 95th cruise of R/V Professor Vodyanitsky in the summer of 2017. The total (particulate + dissolved) ⁷Be activity varied spatially from 2.8 to 8.3 Bq m⁻³ and averaged to 5.3 ± 1.9 Bq m⁻³. The particulate fraction of ⁷Be activity varied spatially between 5% and 13%, with an average value of 8% ± 2%. This paper provides an analysis of the influence of atmospheric precipitation, mixed layer depth, suspended matter concentration (TSM), seawater temperature, and salinity on the spatial variability of ⁷Ве activity. It is shown that the variability of the TSM might determine the spatial heterogeneity of total ⁷Be activity in the study area. Quantitative estimates of the distribution coefficient (Kd) of ⁷Be for the dissolved and particulate phases were obtained, and the functional dependence of Kd on the TSM was established. The average Kd value was determined to be (1.6 ± 0.3) × 10² m³ kg⁻¹. Kd decreased with an increase in TSM. The obtained estimates suggested that the average ⁷Be sinking rate on the particulate matter was (1.3 ± 0.7) × 10⁻⁵ m s⁻¹. Sinking particles removed approximately 7% of total ⁷Be activity from the surface layer offshore and reached 29% on the Black Sea shelf. The influence of the TSM, its sinking rate, vertical exchange intensity, and bathymetry on the ⁷Be sinking flux in the surface mixed layer (SML) were also investigated. A statistically significant correlation was established for both the particle sinking rate and TSM: an increase in the sinking rate and TSM led to an increase in the contribution of the sinking process to the total ⁷Be flux from SML.
https://authors.elsevier.com/a/1cXdy3IHZiC%7Eh1
... Both 10 Be and 9 Be were greatly enriched in organic matter (Lundberg et al. 1983). Bloom and Crecelius (1983) reported a much stronger affinity of 7 Be for inorganic particles (presumably clay minerals) than for organic matter, in marine conditions. Kaste (1999) found that the log K d Be of 7 Be between stream water and stream sediment or Sphagnum was less than for 9 Be but had no explanation, other than possibly an artifact of collection methods. ...
... Note that the value of this coefficient tends to increase as the concentration of suspended matter and salinity decrease. This result agrees with the published data (Bloom and Crecelius 1983;Hawley et al. 1986). The absence of statistically significant correlation between these parameters has two reasons: (i) the influence of these parameters in the range of values under investigation is masked by the error in determining the K d coefficient, and (ii) water with low salinity had higher concentrations of suspended matter (Table 1). ...
The spatial distribution of ⁷Be activity in the surface layer of the Black Sea was studied using the data of field observations made during the 87th cruise of R/V Professor Vodyanitskii. Activity of ⁷Be varied spatially from 4.6 to 9.5 Bq m⁻³ (mean 7.5 ± 1.3 Bq m⁻³) where about 9% was found on suspended matter. The minimum values of activity were typical for samples taken in the shelf waters and the maximum—offshore. The influence of different factors on ⁷Be activity was analyzed. It was revealed that variation of both ⁷Be wet deposition on the sea surface and concentration of suspended matter were the most significant for spatiotemporal variability of ⁷Be activity in seawater during the study period. The estimates of ⁷Be distribution coefficient between dissolved and particulate forms were obtained. This coefficient varied from 1.5·10⁵ to 2.4·10⁵ L kg⁻¹, averaged (1.9 ± 0.3)·10⁵ L kg⁻¹. Full-text is available on https://rdcu.be/6sLU
... Reprinted from Journal of Environmental Radioactivity, 85, Ioannidou and Papastefanou, Precipitation scavenging of 7 Be and 137 Cs radionuclides in air, 121-136., copyright (2006) with permission from Elsevier. 4 orders of magnitude from pH 6 to pH 2. This is consistent with findings of dissolved 9 Be enrichment in riverine systems at pH b 6 (Measures and Edmond, 1983;Brown et al., 1992;Neal, 2003) and similarly Bloom and Crecelius (1983) showed reduced sorption of 7 Be to detritus and Fe (OH) 3 below pH 6. Bloom and Crecelius also found rapid desorption of 7 Be from air particulates upon contact with water owing to the effect of a reduction in pH and You et al. (1989) suggested that such effects reflect the solubility and changing surface charge density of adsorbing hydroxides with decreasing pH. ...
... If this is characterized by a first order rate constant (k p ), then k p / (k p + λ Th ) = 0.2 and k p = 0.25 * λ Th . Bloom andCrecelius (1983), Nyffeler et al. (1984), Li et al. (1984), and Honeyman and Santschi (1988) have reported that the partition coefficient (K d ) of Th (~10 6 L kg −1 ) is approximately an order of magnitude greater than that for Be (~10 5 L kg − 1 ). Thus, k p ′ for 7 Be should be~10% of k p and the loss fraction of 7 Be by particle export should be: k p ′/(λ Be + k p ′) = 0.025 * λ Th / (λ Be + 0.025 * λ Th ), or~5%. ...
Five 7Be profiles, measured in an area bounded by 10°S-20°S and 80°W-100°W, were used to determine upwelling velocity (wH) and vertical diffusivity (Kz). A positive correlation between wH and 14C primary production rate and a negative correlation between the inventories of 7Be and phosphate were observed. We interpret this as the influence of deeper, nutrient-rich, 7Be-poor water brought up by upwelling. Excluding two stations that appear to be influenced by non-steady state dynamics or horizontal transport, upwelling velocities were estimated to be 0 to 1.0 m d- 1 and Kz values ranged from 0.4 to 2.6 cm2 s- 1. From these parameters, NO3- fluxes into the euphotic zone were assessed and ranged from 0.15 to 2.9 mmol m- 2 d- 1. Using these values, we estimate 1.0 to 19 mmolC m- 2 d- 1 of new production in the ETSP. New production based on 7Be-derived transport parameters agree with carbon export estimates using a 234Th balance, sediment traps and O2/Ar supersaturation for stations along 20°S, but are higher than export estimates at 10°S, 100°W.
... Rather, the process of rapid downwashing is more likely driven by the movement of rainwater and the structure of the organic matter, which in some cases facilitates elemental transport without the appropriate solid-solution contact time for adsorption to occur. Most equilibration studies show that metals, including Pb and Be, typically require more than 12 h to reach equilibrium with respect to surface adsorption (Bloom and Crecelius 1983;Nyffeler et al. 1984). Thus, downwashing must occur rapidly during moderate to intense rainfall events where rainwater can quickly penetrate into the peat before adsorption to the top layer can occur. ...
Several factors can affect the integrity of natural archives such as peat records, e.g., decomposition and nutrient cycling, and it has also been hypothesized that some rapid downward transport of atmospherically derived elements may occur. We test this hypothesis by analyzing the short-lived, natural tracer beryllium-7 (tA1/2A = 53.4 days) in five cores from two peatlands. In triplicate hummock cores from a raised bog in southern Sweden, Be-7 could be measured to 20, 18 and 8 cm depth, and in a nutrient-poor mire in northern Sweden to a depth of 16 cm in a Sphagnum lawn core, but only 4 cm in the dominant, more-decomposed fen peat, indicating some spatial variability both within and between sites. Total Be-7 inventories were 320-450 Bq m(-2) in the bog, and 150 Bq m(-2) (lawn) and 240 Bq m(-2) (fen peat) in the mire. 25-79 % of the total inventory of Be-7 was located in the upper 2-cm layer. To further test downwashing, in the laboratory we applied a CuBr-solution to two cores and a Cu-solution to one core taken from the mire Sphagnum lawn, all with low water table conditions. About 50 % of the added Cu and similar to 35 % of the added Br were retained in the surface (2 cm) layer; 1-3 % of the Cu was found at 8-12 cm depth and similar to 1 % of the Br was measured in the lowest level (20-22 cm). Based on our novel approach using Be-7 and experimental work we show that short-term downwashing can occur in peatlands and we suggest the depth of this will depend on the properties of the peat, e.g., bulk density and decomposition, as well as hydrology.
... If this is characterized by a first order rate constant (k p ), then k p / (k p + λ Th ) = 0.2 and k p = 0.25 * λ Th . Bloom andCrecelius (1983), Nyffeler et al. (1984), Li et al. (1984), and Honeyman and Santschi (1988) have reported that the partition coefficient (K d ) of Th (~10 6 L kg −1 ) is approximately an order of magnitude greater than that for Be (~10 5 L kg − 1 ). Thus, k p ′ for 7 Be should be~10% of k p and the loss fraction of 7 Be by particle export should be: k p ′/(λ Be + k p ′) = 0.025 * λ Th / (λ Be + 0.025 * λ Th ), or~5%. ...
Assuming steady-state over seasonal to annual timescales, and limited horizontal export of dissolved nutrients, the vertical fluxes of limiting nutrients into the euphotic zone should be balanced by particle export. Sediment traps and 234Th budgets have both been used extensively throughout the oceans as a means to measure this particulate flux from the upper ocean. One main goal of these efforts has been to determine the amount of CO2 fixed by primary producers in the surface ocean that is exported as particulate organic carbon (POC) and conversely, the decrease of particle flux with depth has been used to estimate remineralization rates of nutrients. Although disagreement between trap-derived and 234Th-derived fluxes has often been noted, the possible reasons for the imbalance are numerous, and thus often it is difficult to assign causes. Here, we examine many commonly implicated contributors to the disagreement, allowing us to assess data from a recent 2-year study in the ETSP that shows systematic disagreement between the two methods. Averaging results from both years, sediment traps collected 0.2–1.5 mmol C m−2 d−1 (mean: 0.74 mmol C m−2 d−1) of POC, while the thorium-based method estimated an average POC flux of 1.5–14 mmol C m− d−1 (mean: 6.2 mmol C m−2 d−1). The study area spans regions of differing ecological structure, as inferred from trap mineralogy, and the flux disagreement coincides with this ecological range. We interpret the difference as undercollection of poorly ballasted, slowly sinking particles by the sediment traps. Using both methods simultaneously offers insight into ecosystem structure and resulting particle flux dynamics. The thorium deficit-based flux is 5–10% of previously published estimates of primary productivity based on 14C incubations (Pennington et al., 2006), and 8–20% of concurrent estimates based on 14C incubations and oxygen supersaturation (Capone et al., personal communication; Prokopenko et al., personal communication).
... Reprinted from Journal of Environmental Radioactivity, 85, Ioannidou and Papastefanou, Precipitation scavenging of 7 Be and 137 Cs radionuclides in air, 121-136., copyright (2006) with permission from Elsevier. 4 orders of magnitude from pH 6 to pH 2. This is consistent with findings of dissolved 9 Be enrichment in riverine systems at pH b 6 (Measures and Edmond, 1983;Brown et al., 1992;Neal, 2003) and similarly Bloom and Crecelius (1983) showed reduced sorption of 7 Be to detritus and Fe (OH) 3 below pH 6. Bloom and Crecelius also found rapid desorption of 7 Be from air particulates upon contact with water owing to the effect of a reduction in pH and You et al. (1989) suggested that such effects reflect the solubility and changing surface charge density of adsorbing hydroxides with decreasing pH. ...
Beryllium-7 is a cosmogenic radionuclide formed in the upper atmosphere
by cosmic ray spallation of nitrogen and oxygen. Its constant natural
production and fallout via precipitation coupled with its ability to
bind to soil particles have underpinned its application as a sediment
tracer. The short half-life of beryllium-7 (53.3 days) lends itself to
tracing sediment dynamics over short time periods, thus, enabling
assessment of the effect of land use change upon soil redistribution.
Although beryllium-7 has been widely applied as a tracer to date, there
remain crucial gaps in understanding relating to the assumptions for its
use. To further support the application of beryllium-7 as a tracer
across a range of environments requires consideration of both the
current strengths and shortcomings of the technique to direct research
needs. Here we review research surrounding the assumptions underpinning
beryllium-7 use as a tracer and identify key knowledge gaps relating to
i) the effects of rain shadowing and vegetation interception upon
beryllium-7 fallout uniformity at the hillslope-scale; ii) the effect of
preferential flow pathways upon beryllium-7 depth distribution in soil
and overland flow upon beryllium-7 inventory uniformity and iii) the
potential for beryllium-7 desorption in saline and reducing
environments. To provide continued support for the use of beryllium-7 as
a hillslope and catchment-scale tracer, there is an urgent need to
undertake further research to quantify the effect of these factors upon
tracer estimates.
... The material that deposits on these tiles tends to be high in organic content, often like "coffee grounds" in texture. This highly organic material could effectively dilute the 7 Be signal, since 7 Be tends to attach to inorganic, muddy sediment (Bloom and Crecelius, 1983). It also could be sediment that is imported from the nearshore, where it may have been sequestered from the atmosphere long enough for its 7 Be signal to decay. ...
... Casey et al. (1986) showed further contrast with no significant change in K d (values of 10 4 ) between salt marsh sediment and pore waters of varying salinity, which is supported by Olsen et al. (1986). The influence of pH upon Be sorption has been highlighted by numerous studies: You et al. (1989) demonstrated the pH dependency of 7 Be partitioning using a range of substrates, showing a K d decrease of 4 orders of magnitude from pH 6 to pH 2. This is consistent with findings of dissolved 9 Be enrichment in riverine systems at pH b 6 (Measures and Edmond, 1983; Brown et al., 1992; Neal, 2003 ) and sim- ilarly Bloom and Crecelius (1983) showed reduced sorption of 7 Be to detritus and Fe (OH) 3 below pH 6. Bloom and Crecelius also found rapid desorption of 7 Be from air particulates upon contact with water owing to the effect of a reduction in pH and You et al. (1989) suggested that such effects reflect the solubility and changing surface charge density of adsorbing hydroxides with decreasing pH. Although caution should be given to direct comparison of K d values between studies owing to variations in the methods applied (Krupka et al., 1999), findings do suggest a complex pattern of 7 Be interaction with water and sediment in the natural environment. ...
This contribution reviews research surrounding the assumptions that underpin the use of beryllium-7 (7Be) as a soil and sediment tracer in river basins. As a cosmogenic radionuclide, the constant natural production of 7Be and fallout via precipitation, coupled with its ability to bind to soil and sediment particles provides the basis for its application as a conservative soil and sediment tracer. Consequently, 7Be has been extensively employed as a tracer across a range of spatial and temporal (event to seasonal) scales. The short half-life of 7Be (53.3 days) lends itself to tracing sediment dynamics over short time periods, thus, providing complementary data to medium-term estimates derived from longer lived radionuclides such as caesium-137 (137Cs). This short half-life could provide a major advantage when considering the potential for 7Be to document recent effects of climate or land use change upon soil redistribution, with the latter having particular relevance for assessing the effectiveness of mitigating strategies within a catchment-wide approach to management. Although 7Be has been widely applied as a tracer to date, application is still in its infancy and there remains a lack of knowledge in relation to the assumptions for its use as a tracer. Specifically, our findings suggest that there are crucial information gaps with regard to 7Be application as an erosion tracer. Of key importance is the potential for fallout uniformity and rapid tracer sorption to be compromised under certain conditions. The assumption of irreversible sorption is likely to hold for common hillslope conditions but literature identifies the potential for tracer mobility with changing environmental parameters in the wider catchment. Further research is required to determine the likelihood of 7Be sorption being affected by conditions found at relevant field sites and the impact of this upon tracer applications at the catchment-scale.
... Therefore, we suggest that the mean activity of recently deposited sediments (A catch ) was greater than the measured 7 Be activity of suspended particles in the marsh tidal creek (2·3 and 9·1 dpm g 1 ). Preferential binding of 7 Be to inorganic over organic particles or fine-grained versus sandy particles may explain our relatively low particle-specific 7 Be activities (Bloom & Crecelius, 1983). At Sweet Hall, the maximum suspended particle concentrations and minimum percent of organic particles (20 to 25% organic; range for 10 tidal cycles) were measured approximately midway between slack tides -this was also near the time when the marsh was first flooded. ...
Sedimentation rates were measured from May 1998 to March 1999 at Sweet Hall Marsh, a tidal freshwater marsh in the Coastal Plain of Virginia using various techniques (sediment catch plates, triangular survey method, Be-7 distribution). Rates of sedimentation vary spatially and temporally in the marsh. Sedimentation rates are generally greatest adjacent to a tidal creek and decrease progressively farther into the marsh. Differences in rates of sedimentation are greatest spatially during the summer and are least during the winter. Accuracy of rates calculated depend on the methods used to measure sedimentation. A combination of methods likely provides the most accurate trends of sedimentation change. The organic content of marsh sediment may influence marsh stability indirectly and also varies spatially and temporally. Organic content generally increases farther away from sediment sources in the marsh; increased organic content in interior parts of Sweet Hall Marsh may promote increased rates of respiration and thus greater loss of total sediment fraction. Organic content seems to correlate with decreased carbon/nitrogen ratios and increased respiration rates. The general evolution of Sweet Hall Marsh was described using evidence obtained from vibracoring and carbon-14 dating. Along with stratigraphic evidence, organic content of marsh sediment was analyzed with depth to depict the history of the marsh.
... The minimal variability of 9Be with salinity in the Ganges-Brahmaputra mixing zone up to ~ 20%o salinity may provide evidence for desorption of particulate 9Be during estuarine mixing. However, in view of experimental [42,43] and observational [19] studies, which have demonstrated that partitioning of Be on to suspended particles increases with pH, we suggest that desorption is unlikely and instead propose that the observed distribution is evidence of inhomogeneity among the mouths of the Ganges. ...
An understanding of the geochemistry of the cosmogenic radioisotope 10Be (t1/2 = 1.5 My) and the stable isotope 9Be is necessary for the development of their use in deep-sea sediments as a geochronometer and as a monitor of variations in cosmogenic nuclide production. We examined these isotopes in oceanic regions strongly influenced by input of continental materials; the effects of atmospheric aerosols were studied through examination of the water column chemistry of the Mediterranean (a basin strongly influenced by Saharan dust) while salinity transects through the Amazon and Ganges-Brahmaputra estuaries were used to investigate riverine fluxes to the oceans. These results were used to quantify riverine and eolian fluxes; they indicate that eolian dust is probably the most significant source of 9Be to the oceans. Changes in 10Be:9Be in the marine sedimentary record which are not associated with radioactive decay or variability in 10Be production can thus result from local or regional changes in dust inputs.
... As the concentration of SPM did not show large increases, the K d value was largely controlled by the salinity and not by the SPM Fig. 3 indicates that K d values also decreased with SPM concentration in both rivers. In Sequim Bay, it was reported to be as high as w50% of the 7 Be that was found in the particulate phase, with SPM concentrations of w20 mg L À1 at salinity ca 30% (Bloom and Crecelius, 1983). In the Wenjiao/Wenchang and Wanquan River estuaries, the percent of particulate 7 Be was also as high as w50%, whereas the fraction of particulate phase 210 Pb was typically much higher than 50%. ...
Radionuclides (i.e., 7Be and 210Pb) can be used to trace particle and sediment dynamics and to quantify coastal oceanic processes with time scales ranging from a few days to a hundred years. Here, we study the settling dynamics of suspended particles and the implication by sedimentary heavy metals in the Wenjiao/Wenchang River and Wanquan River estuaries through the measurement of the particulate 7Be and 210Pb nuclides. Activity in the particulate phase had a range of 2.1–54.5 and 4.6–67.9 Bq kg−1 for 7Be and excess 210Pb (210Pbxs), respectively, in the Wenjiao/Wenchang River estuary. In the Wanquan River estuary, activity is in the range of 1.2–43.5 Bq kg−1 for 7Be and 6.2–194.5 Bq kg−1 for 210Pbxs. At the same time, activity in the dissolved phase had a range of 0.46–1.26 and 0.30–1.17 Bq m−3 for 7Be and 210Pb, respectively, in the Wenjiao/Wenchang River estuary; ranges of 0.10–2.31 and 0.09–1.87 Bq m−3 for 7Be and 210Pb, respectively, were observed in the Wanquan River estuary. The distribution coefficients (Kd) for the two nuclides decreased within increased in suspended particle matters (SPM) concentration and/or salinity in Wanquan River estuary. The residence times of particulate 7Be and 210Pbxs had ranges of 0.4–1.6 and 1.65–5.15 days, respectively, in the Wenjiao/Wenchang River estuary; and ranges of 0.02–3.2 and 0.61–4.44 days, respectively in the Wanquan River estuary. All residence times for the two nuclides increased in the seaward direction. In the Wenjiao/Wenchang River estuary, we found that 11.8–21.0% of Cu, 3.0–9.0% of Zn and 43.2–69.9% for Cd is removed from the water column and deposited into the estuary, and 24.2–34.8% for Cu, 7.2–23.8% for Zn, and 70.0–82.5% for Cd in the Wanquan River estuary, respectively.
... Be cm -2 . Both 10 Be and 9 Be were greatly enriched in organic matter (Lundberg et al. 1983). Bloom and Crecelius (1983) reported a much stronger affinity of 7 Be for inorganic particles (presumably clay minerals) than for organic matter, in marine conditions. Kaste (1999) found that the log K d Be of 7 Be between stream water and stream sediment or Sphagnum was less than for 9 Be but had no explanation, other than possibly an artifact of collection metho ...
Beryllium is a rare but widely distributed element. As a consequence of rapid developments in the capabilities to determine low concentrations of Be in inorganic solids, tissue, air, and water, it is now possible to characterize the distribution of Be in various environmental compartments, to describe the fluxes among these compartments, and to determine the controls on these fluxes. Increased human activity, including land disturbance, metallurgical processes, the burning of fossil fuels (with associated air pollution, including Be, and related terrestrial acidification), has generally increased the flow of Be through ecosystems. This fact was recognized several decades ago (e.g., Kubizňáková 1983). The distribution and distribution of Be nuclides are important to understand because of Be toxicity to fauna (including humans) and possibly to flora. The radioisotopes (7Be and 10Be) are used to understand environmental and geologic processes. Because of the very different half lives (7Be = 53 days; 10Be = 1.5 million years), Be nuclides have been used to study earth-surface processes as short as diurnal variation (EL-Hussein et al. 2001) to exposure age-dating (Braucher et al. 2000) and erosional processes (Small et al. 1999). Consequently, we review the literature from the perspective of the interaction of geologic materials, aqueous solutions, and biota, at or near Earth´s surface. This chapter is organized parallel to the hydrologic pathways from the atmosphere, through ecosystems, to estuaries. We focus on the environmental chemistry of the stable nuclide 9Be, whereas Kaste et al. (this volume) focus on the cosmogenic isotope 7Be and Morris et al. and Bierman et al. focus on 10Be. Effects of point-source pollution on the immediate environment, such as in the vicinity of smelters, are not discussed except where the effects may be transmitted regionally by the atmosphere or surface water.
... 7 Be, produced in the atmosphere by cosmic-ray spallation of oxygen and nitrogen, is rapidly associated with aerosols and supplied to the earth's surface by precipitation and dry deposition. Once in the terrestrial and marine environments, 7 Be quickly adsorbs onto particles (Bloom and Crecelius, 1983; Olsen et al., 1986). Like 7 Be, 137 Cs (30.2 years) was supplied to the earth's surface by precipitation and dry deposition. ...
Large rivers are the primary interface between terrestrial and ocean environments. A relatively small number of rivers account for a disproportionate amount of the freshwater and suspended materials that are delivered to the coastal ocean. Sediment delivery to these coastal systems plays a key role in the global carbon cycle since deltas and continental shelves are considered to be the main repositories of organic carbon in marine sediments. Particulate material in these environments are typically deposited and resuspended several times before permanent accumulation or transport off the shelf. This sediment cycling is an important component influencing biogeochemical processes that occur in coastal environments. During two cruises in April and October 2000 on the shelf adjacent to the Mississippi River, water and sediment samples were collected for analysis of suspended solids and particle reactive radionuclides (²¹⁰Pb, ¹³⁷Cs, ⁷Be and ²³⁴Th) to evaluate the transport and fate of terrestrial and marine material. A comparison of the distribution of these tracers provides insight about the pathways and residence times of particulate materials on the shelf. Inventories of these short-lived radiotracers showed variations of more than two orders of magnitude, indicating dramatic variations in sediment deposition between sampling events.
... Distribution coefficients calculated from 7Be in natural systems must be viewed with caution. Experimental work has shown that equilibration of Be between the dissolved and particulate phases requires three or more weeks, on the order of the half-life of 'Be (BLOOM and CRECELIUS, 1983;BAL-ISTRIERI and MURRAY, 1984;LI et al., 1984;NYFFELER et al., 1984;YOU et al., 1989). In addition, the input of 'Be may be quite variable at a single site (TUREKIAN et al., 1983;DOMINIK et al., 1987), and sediment loads can also vary substantially on short time scales; so, as pointed out by OLSEN et al. ( 1986) and BLOOM and CRECELIUS ( 1983), freshwater systems may not be at steady state. ...
The distributions of beryllium-9 and beryllium-10 in rivers within the Orinoco and Amazon basins have been examined to extend our understanding of their geochemical cycles and to develop their use both in geochronometry, and in studying erosional processes. Beryllium-9, the stable isotope, is weathered from mineral lattices before entering the riverine dissolved or exchangeable phase. The cosmogenic radioisotope ¹⁰Be ( ) is produced primarily in the atmosphere and is brought into riverine systems, via rainfall, in dissolved or exchangeable form; it may be used to examine the processes which affect beryllium partitioning between the dissolved and particulate phases. Ancillary data, such as major ion distributions, provide a basis for selecting regions in which riverine chemistry is dominated by a single geochemical process, allowing examination of its effects on Be distributions in isolation.
This chapter discusses the biogeochemical cycling of primarily toxic and persistent compounds, such as Pu isotopes, 210Po, 210Pb, As, Hg, and polynuclear aromatic hydrocarbons. It describes the major improvements—such as sample collection, preparation, and analytical chemistry capabilities for the determination of trace organic compounds, stable metals, and their speciation and radionuclides in environmental samples—in studies of chemical cycling off the Washington coast. The chapter discusses various processes such as chemical inputs from rivers, advecting seawater, air–sea exchange, and hydrothermal activity as well as outputs to the major sedimentary and biological reservoirs via uptake and exchange of chemicals with water column. The chapter describes the cycling of chemicals on the open Washington coast north of the Columbia River mouth. Related research in the Strait of Juan de Fuca and in Puget Sound is compared and contrasted in the chapter.
Beryllium-7 is a cosmic-ray-produced radioactive nuclide (half-life 53.3 days) that is deposited upon the ocean surface by rainfall. Beryllium-7 profiles were collected and analyzed in May 1991 and March 1992 as part of the ONR SUBDUCTION program. The 7Be activities were homogeneous in the mixed layer and ranged approximately from 100 to 200 dpm/ 1000 1. The activities dropped off rapidly in the upper thermocline. The 7Be profiles were modeled using a simple seasonal progression of mixed-layer depth, indicating that seasonal changes in the mixed-layer depth control the main features of the profile. The observed temperature, salinity and 7Be profiles from the May 1991 cruise show warm salinity maxima associated with a layer of high 7Be penetrating into the upper seasonal thermocline. The high 7Be concentration suggests that these waters were in relatively thin mixed layers within, approximately, the past month. The model results indicate that in late spring both salinity and 7Be can respond to a shoaling mixed layer on a similar timescale leading to the observed anomalies in the subducted water layer.
Current understanding and data are presented and summarized regarding
Be-10 in the environment. A preliminary global Be-10 cycle is presented
to enhance the use of Be in the earth sciences. Data are detailed
regarding the presence of Be-10 in the atmosphere, glacial ice, and
soils. The transportation and sedimentation of this cosmogenic
radionuclide and its contribution to seawater, authigenic deposits, and
deep-sea sediment composition are described. A short description of the
relationship between volcanism and Be-10 follows. Finally, a complex
diagram of the global Be-10 cycle is presented, in which the flux into
and out of each reservoir is balanced. The results emphasize that Be-10
is a rare component in the global geochemical system. The production
rates of Be-10 set forth by earlier studies approach the budget
constructed here.
The greylag goose and wigeon are both traditional quarry of wildfowlers. Populations of these birds in the Ravenglass estuary feed and roost on saltmarshes containing radioactivity originating from the Sellafield reprocessing plant. There is therefore, via the meat, a potential pathway for the transfer of radionuclides to man.The birds' intake of gamma-emitting fission and activation products, including 60Co, 95Nb, 95Zr, 106Ru, 144Ce, 134Cs, 137Cs, 154Eu, 155Eu and 241Am, was investigated by examining their concentrations in vegetation from feeding areas and in their faeces. Muscle and liver tissues were also analysed. Only 134Cs and 137Cs were detected and quantified in breast muscle; 58 Bq kg−1 and 158 Bq kg−1 fresh weight were recorded for goose and wigeon respectively. Estimated transfer coefficients for 137Cs were very similar for both species; 5·9 × 10−1dkg−1 for greylag goose and 5·7 × 10 −1 d kg−1 for wigeon.A single person would have had to consume in excess of the total number of wigeon shot or the total population of geese to obtain even 1% of his or her Annual Limit on Intake. In a ‘worst case’ scenario, wigeon could have transferred 5·63 MBq (152 μCi) of 137Cs inland from the tidal areas of the estuary but, because they never fed above the tide line, they, in fact, transferred no radionuclides inland during the study period.
An extensive and systematic investigation of Be partition between solid and water was carried out using laboratory batch experiments with radioactive 7Be tracer. We found that: (1) Be is strongly held by the solid particles in natural environments under neutral conditions; (2) man-made δ-MnO2 and in situ weathering products of andesite have the highest Kd (> 106) while most mud, silt and clay minerals have Kd on the order of 105; (3) Kd is high under neutral or alkaline conditions but decreases rapidly by four orders of magnitude between pH 6 and 2; (4) Kd decreases with increasing concentration of suspended particles; (5) dissolved organic matter in Taiwan Strait surface water does not seem to greatly affect the value of adsorption Kd; (6) adsorption of Be onto soil is a two-stage process and the second stage is ∼ 1000 times slower than the first; (7) the reaction of surface ion exchange seems to proceed at a faster rate in river water than in seawater, probably because of the high ionic strength of the latter; (8) the activation barrier of sorption reaction for Be seems to be ∼ 10 kcal.mol−1 for river mud; and (9) the adsorption of Be onto soil seems to be a reversible process.
Short-term sediment accumulation rates were determined using activity distribution of â·Be in the surficial sediments of a station (A-1) in Cape Lookout Bight, North Carolina (USA). This semi-enclosed coastal marine basin is characterized by high annual accumulation rates. Protected from high energy conditions by its geomorphology, the relatively quiescent waters of the bight's interior cause it to act as an efficient settling trap for fine-grained sediment. Lack of bioturbation in the surface sediments allowed for variations in depth-integrated activity profiles of â·Be to be interpreted as short-term accumulation events. Beryllium-7 inventories exhibited seasonal cyclicity with maxima occurring during spring (February through June). The inventory of â·Be ranged from 5.8 to 32.6 dpm cmâ»Â² and was always well in excess of the atmospherically supported value ({bar x} = 3.8 dpm cmâ»Â²; n = 15). Accumulation rates calculated from â·Be activity profiles indicate that the delivery of particulate matter to the sediments of Cape Lookout Bight is not constant throughout an annual cycle. The highest monthly accumulation rates appeared to be associated with north/northeastern storm activity. Inputs were generally highest during late winter/early spring when storm frequency is greatest. Short-term accumulation rates derived from this study agree with ²¹°Pb rates calculated for a ten-year period of accumulation. The annual sediment accumulation rates for each of the two years over which the study was conducted was found to be 4.8 {plus minus} 0.8 g cmâ»Â²yâ»Â¹ and 3.7 {plus minus} 1.2 g cmâ»Â²yâ»Â¹.
Environmental radionuclides—in combination with stable isotopes, geochemistry, and other hydrological techniques—provide a powerful tool, often indispensable, for studying the cycling of water in continental hydrological systems. The use of environmental radionuclides in surface water studies is reviewed in the chapter. The chapter also briefly discusses groundwater and geothermal water taking into consideration the fact that most applications in groundwater and geothermal water studies require the combined use of radioactive and stable isotopes. There are several sources of radionuclides in the environment, and the sources control the ways in which isotopes can be applied to hydrologic systems. Another group of radionuclides that can be utilized are those produced by cosmic-ray spallation in the atmosphere or near-surface lithosphere. Many of these nuclides, such as carbon-14 (¹⁴C) and tritium (³H), are also produced by nuclear weapons testing, and it is necessary to separate the two source functions when using them.
Suspended sediment was collected in the South Slough, National, Estuarine Research Reserve, Oregon, over 8 tidal cycles during
and following a single runoff event. The sediment was analyzed for its radionuclide signature to determine the relative contributions
of different sources of sediment to the efflux from the estuary. Suspended sediment in the estuary is a mixture of sediment
from three potential sources: the river system, Coos Bay, and the estuarine bed. Each source material has a distinctive7Be:210Pbxs ratio. The ratios of the source sediments decreased, in magnitude in the following order: riverine >bay>bed. The ratios,
of the suspended sediment collected within a subsection of the South Slough estuary reflected the relative mixture of the
source areas. The7Be:210Pbxs ratios provided a means of not only differentiating, between resuspended bed sediment and freshly delivered sediment from
both the river system and Coos Bay, but also calculating the relative amount of resuspended bed sediment in the suspended
sediment collected in the estuary. The sampled subsection of the South Slough estuary was a net sink of sediment during a
100-h sampling period associated with the runoff event, but the radionuclide analysis suggests that approximately 39% of the
sediment efflux was resuspended bed sediment.
The atmospheric flux of cosmogenic â·Be (53.3-day half-life) and the mode of â·Be deposition in river-estuarine and coastal environments have been examined. The atmospheric flux of â·Be commonly supports inventories ranging from 1.0 to 2.0 pCi/cm² (1 pCi = 0.037 Bq). Beryllium 7 concentrations in water phase samples, collected across gradients in several estuaries along the eastern coastline of the United States, range from 0.03 to 0.53 pCi/L and primarily reflect variations in â·Be supply and sorption kinetics. The major process controlling the concentration of â·Be on estuarine suspended particles appears to be the length of time that these particles remain in the water column. Field particles-to-water distribution coefficients for â·Be have a median value of about 4 x 10â´ but range over an order of magnitude reflecting short-term variations in â·Be input, particle dynamics and particulate iron content rather than equilibrium sorption-desorption responses to changes in water salinity or particle type. Residence times of â·Be in the water column range from a few days in estuarine areas of rapid fine-particle deposition, to several weeks in high-energy environments where pronounced sediment resuspension reintroduces deposited â·Be back into the water column. Inventories of â·Be in sediments range from nondetectable to 3.3 pCi/cm², with the highest inventories in areas where fine particles are accumulating rapidly. Such sites are also major repositories for other particle-reactive substances. A â·Be budget for the James estuary indicates that less than 5% of the expected â·Be input is in the water column and that the short-term estuarine trapping efficiency for atmospherically derived â·Be is somewhere between 50 and 100%.
Multiple box cores were collected on the continental shelf in the Mississippi Deltaic Region adjacent to Southwest Pass and analyzed for particle reactive radionuclides 234Th and 7Be to examine seasonal sediment dynamics associated with variations of river discharge and hydrodynamics. Three stations located along a line west of Southwest Pass were cored and reoccupied in October, November, and December of 2003 and March, April, and May of 2004. High-frequency sampling (∼monthly) comparable to the short half-life of the radiotracers (234Th t1/2=24.1d; 7Be t1/2=53.3) enabled us to isolate the relative influence that various forcing agents (river discharge, waves, currents) had on sediment inventories of 7Be and 234Th. In addition, the primary source of 7Be (fluvial) differs from 234Th (marine), providing further insight into processes affecting sediment transport and supply. Monthly 7Be inventories showed a significant positive relationship to river discharge (P=0.03) proximal to Southwest Pass. Sites further from Southwest Pass exhibited little to no relationship between 7Be inventories and river flow. At these sites, monthly 7Be inventories demonstrated a significant positive relationship with average wave orbital velocity (P
The grain size effects associated with the adsorption of cosmogenic 7Be on basalt were studied experimentally by γ-ray spectroscopy. Samples of macroscopic basalt stones, with diameters between 0.5–50mm, were used to find a power-law relationship between 7Be relative concentration and the diameter of the stones. It is shown that 7Be accumulates on the surface of the basalt, and that stones of smaller grain sizes show more 7Be relative adsorption than those of large ones. No evidence of the volume effect for the 7Be relative concentration was found over the diameter range of the samples.
Measurements of 7Be and oxygen isotope (18O/16O) ratios from the 1997-1998 SHEBA experiment were used to trace the source of the high heat and freshwater content of the upper ocean observed during the initial occupation of the SHEBA site in October 1997. The evidence suggests that the heating resulted from local input primarily through extended lead coverage in the late spring and summer of 1997 with no requirement of advective input. The freshening was derived from a large ice melt (1.2 m) that was consistent with the thin ice and extensive melt pond coverage (by then frozen) observed at the site. However, a significant contribution to the freshwater budget (0.8 m) included enhanced input from river runoff during the melt season. This obviates the requirement for an unrealistically large ice melt (~2 m) to account for the freshwater content of the mixed layer, and would have increased the stratification stability of the upper ocean that in turn would have promoted local heating. The question then arises, however, as to the fate of the significant upper ocean heat at SHEBA in the fall 1997 which resulted from an active heating season. Similar evaluation of the fall 1998 SHEBA site indicate that the ice melt was comparable to that of 1997, but the riverine input and stored water column heat were less than in the previous year.
The dissolved and particulate activities of 7Be in surface and deep water samples from four stations in the main stem of Chesapeake Bay were determined seven times between April, 1986 and April, 1987. Total water column concentrations ranged from < 0·05 to 3·86 dpm l−1, with an average of 0·50 dpm l−1. Batch adsorption experiments indicated a strong affinity of Be for Chesapeake Bay seston, but 7Be in the Bay was predominantly in the dissolved phase. Particulate 7Be activities reached 150 dpm g−1, but averaged 18 dpm g−1, suggesting that rapid variations in the supply of both 7Be and suspended particulates rarely allowed equilibrium partitioning of 7Be between the dissolved and particulate phases.A 7Be budget for Chesapeake Bay indicated that atmospheric deposition was always the dominant source of 7Be in the Bay. Generally, ≥ 95% of the 7Be delivered to the Bay was retained by it. Most (usually > 80%) of the 7Be in Chesapeake Bay at any time was found in the sediments.
Historically, Tampa Bay has been impacted heavily by a wide range of anthropogenic perturbations that may include, agricultural-, shipping-, phosphate mining/distribution-related activities, as well as a burgeoning coastal population. Due to the presence of U-rich underlying sediments, elevated activities of U- and Th-series daughter products may be naturally released into this system. This region is also known for summer thunderstorms and corresponding increases in precipitation and surface water runoff. Only limited work has been conducted on the partitioning of particle-reactive radionuclides (such as 7Be, 210Pb, and 234Th) in such a dynamic coastal system. We investigated both the removal residence time and partitioning of these radionuclides between filter-retained particulate matter (≥0.5 μm) and the filtrate (
Two observed characteristics of Th isotope and stable metal sorption in natural aquatic systems are seemingly at odds with physico-chemical adsorption theory: (1) characteristic sorption times of days to weeks and (2) Kds which are inversely related in magnitude to particle concentrations. In addition, sorption rate constants are positiveiy correlated with particle concentrations and Kd.
This paper presents a conceptual and mathematical model with which it is proposed that these metal sorption characteristics have the same underlying physical process in common: the coagulation of colloidal (nonfilterable) particles onto larger (filterable) particles. “Brownian pumping” (the transfer of truly dissolved metal species to filterable particles through a colloidal intermediate) consists of two rate steps: (1) rapid formation of metal/colloid surface site complexes (adsorption) and (2) slow coagulation of colloids with filterable particles. The Brownian-pumping model is tested against field and laboratory data. The field data, obtained from the literature, covers different regions of the oceans: deep ocean environments, euphotic zone, coastal and estuarine systems. The laboratory data involved ²²⁸Th sorption in suspensions of goethite and polystyrene latexes. Although the model has general applicability, results and discussions herein emphasize thorium isotope behavior. The Brownian-pumping model suggests that Th or other strongly sorbing elements may be useful as in situ “coagulometers” either at relatively high (e.g., greater than 5–10 mg/l) particle concentrations or when the mass ratio of colloids (C*p) to filterable particles (Cp) is known. The model also indicates that the ratio of colloids to filterable particles in marine systems, may be, by a first approximation, described by the relationship log C*p = 0.7 log Cp – 2.6 (in units of kg/l).
Sediment deposition and accretion rates in a Virginia tidal freshwater marsh were measured to provide insight to the processes and time scales that are important for maintaining marsh surface elevation. Short-term sediment deposition rates (biweekly to monthly) measured using sediment collection tiles were spatially and temporally variable. Rates were greatest near a tidal creak and decreased along a transect extending toward the marsh interior. When integrated across the entire marsh, annual sediment deposition (as organic carbon) averaged 517353 g C m 2 y 1 and was sufficient to balance the effects of existing relative sea level rise and marsh respiration rates. At the creekbank, the highest deposition rates were measured during summer although rates were relatively constant over time at the interior sites. Similar spatial and temporal patterns were obtained when deposition rates were calculated from 7 Be inventories (monthly time scale). Sediment inventories of 7 Be were greater than those supported atmospherically, indicating that the spatial patterns of sedimentation were not due to sediment erosion and redistribution within the marsh. Accretion rates calculated from 137 Cs (decadal scale) and 14 C dating (centuries to millennia) were substantially less than annual deposition rates, with a decrease in accretion rate with increasing time scale. Mineralization rates of recently deposited sediments (measured as O 2 consumption) indicated that sediment metabolism could potentially remove 30% of recently deposited carbon within one month of deposition. The metabolism of a labile sediment fraction could explain a portion of the observed decrease in accretion rate with increasing time scale, with the remainder due to periodic storm-induced erosion and historical variability in sediment deposition rates.
The influx of10Be into a globigerinid ooze core (CH72-02) from the eastern North Atlantic has been studied. This core contains a depositional record of the first 11 δ18O stages covering the last 423 ka. It is shown that the marine deposition of10Be is strongly influenced by the sedimentation of clays. Clay particles appear 10 times more efficient than the carbonate component as a carrier in bringing10Be to the bottom sediments. In core CH72-02, the deposition rates of10Be averaged over each oxygen-isotope stage for the past 11 stages show a scatter of ±40% about the mean value of 6.6 × 108 atoms cm−2 ka−1. However, after correction for changes in lithology, the data show that the production rate of10Be over the same period has varied no more than ±25%, and the variations are not systematic in that high or low10Be production appear to be associated with either cold or warm climates. On the time scale of this investigation (intervals of ca. 50 ka over the last 420 ka, with resolutions as fine as 10 ka for portions of the record), it is unlikely that the shielding effect of the solar wind has deviated by more than ±25% or the geomagnetic field intensity has deviated by more than a factor of 1.6 from their long-term averages.
Field observations and experimental measurements of the partitioning coefficient (Kd) of7Be in fresh water show that it varies inversely with the solids concentration at typical environmental values (up to 30 mg/1). This behavior is similar to that of many other metals and organic pollutants, which means that 7Be may be useful as a tracer of the movement of these substances in the water column. However, the wide range in the percentage of 7Be adsorbed by solids over this range of concentrations (over 50%) means that in order to use 7Be either to measure total sedimentation rates or to trace lateral sediment movement it will be necessary to monitor changes in sediment concentration over the area and time period of interest. The wide scatter in our data at both high and low solids concentrations suggests that other factors also affect Kd. Until these factors are identified, application of our results to other systems will be risky. At high (greater than 100 mg/1) solids concentrations over 90% of 7Be is associated with the solid phase, so it may be a useful tracer of reworking rates in bottom sediments. 7Be has a slightly greater affinity for the solid phase in fresh water than in seawater.
The extreme Rhône River flood that peaked in early December 2003 with water discharges as high as 11,500 m3 s− 1, induced major damage in southern France and transferred large amounts of radionuclides that were associated with suspended particulate matter such as 7Be, 137Cs and 210Pb. Specific marine locations in the close vicinity of the Rhône River Mouth were sampled three times in December 2003, February 2004 and April 2004 in order to quantify the consequences of flood events in the Rhône River Prodelta and to investigate the sedimentary depositional patterns through time. The 210Pbxs profile analyses in sediment revealed the existence of two particulate matter inputs, one that was related to the December extreme flood and the other to a peak flood of 4000 m3 s− 1 of water discharge that occurred in January 2004. The December event net deposition was assessed at 75 ± 19 GBq of 210Pbxs and 27 ± 2 GBq of 137Cs. The net deposition in response to the January 2004 flood event, although less damaging, is of the same order of magnitude to the December 2003 deposition, i.e. 71 ± 21 GBq of 210Pbxs and 16 ± 5 GBq of 137Cs. The sedimentary records of the December flood exhibited from the cores collected in December 2003, February 2004 and April 2004 are similar arguing for good environmental signal preservation through time but, the standard deviation of flood deposition estimate increases with time after the December flood event indicating a loss of accuracy with time.
The main definitions involving time concepts in dynamic systems are reviewed and extended. It is shown that a better understanding of aquatic systems can be achieved taking into consideration their mean age (either shorter or longer than the residence time). This time concept is especially useful when the well-mixed hypothesis is not applicable. Two box models are used as examples to demonstrate the relations between residence time and mean age. Then, these time concepts are extended to non-steady state.In the second part, the relationships between them and the behaviour of chemical components in dynamic systems is studied; the importance of radionuclides whose decay is perfectly known is demonstrated.Finally, as application to the Gironde estuary (France) is attempted using a cosmic ray-produced radionuclide, 7Be, whose half-life is especially relevant to macrotidal estuarine dynamics. Particulate concentrations range from 0.2 to 11.2 pCi g−1, while dissolved concentrations are in the range 10 to 50 fCi l−1. The 7Be mass balance is not equilibrated given the residence time computed from sediment discharge and the total mass of sediment in the turbidity maximum. This can be explained by an underestimation of the total mass of sediment involved in resuspension phenomena, or by a difference between the residence time and the mean age of sediment in the turbidity maximum which invalidates the usually implicit well-mixed hypothesis.
Vita. Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Earth, Atmospheric, and Planetary Sciences, and Woods Hole Oceanographic Institution, 1990. Includes bibliographical references.
The concentrations of suspended matter and particulate Cd, Cu, Pb and Zn were determined for 36 samples collected at 6 stations in the Antarctic Ocean during December, 1970 and January, 1971 using membrane filters. The concentration of suspended matter was determined gravimetrically and trace metal levels were determined using anodic stripping voltammetry. For waters deeper than 100 m the concentration of suspended matter was < 100 μg l−1. Concentrations up to 542 μg l−1 were recorded between surface and 100 m. Individual concentrations of the metals were scattered with depth. Average concentrations of particulate metals were: Cd, 3.5 ng l−1; Cu, 100 ng l−1; Pb, 35 ng l−1; and Zn, 230 ng ;l−1 These measurements represent non-steady state conditions of early Antarctic summer as the ice pack disintegrates and biological activity increases.
Complete isotherms of adsorption density vs. pH and concentration have been determined for Co(II) adsorption on SiO2 (point-of-zero charge pHPZC = 2.0) and TiO2 (pHPZC = 5.6). Isotherms for Fe(III), Cr(III), and Ca(II) on SiO2 have also been determined as a function of pH at fixed added concentration.The adsorption data indicate that the primary hydration sphere of free or hydrolyzed metal ions is not altered in the adsorption process. While a specific adsorption potential of ca. −5 kcal mole−1 exists for Co2+ adsorption on TiO2, for SiO2, it is −2 kcal mole−1, or less.Adsorption does not show a simple plateau monolayer behavior, but rather a steady trend with pH and concentration to saturation at the precipitation condition. The qualitative correlation between adsorption and hydrolysis is shown to break down when examined in detail. A complete description is shown to require many interactions for all hydrolysis products and the free ion.
Cosmogenic 7Be (t1/2 = 53.3 days) has been used to estimate particle-mixing rates in the upper layers of lacustrine and near-shore marine sediments. Excess 210Pb and/or 239,240Pu have provided limits on rates of sediment accumulation in these environments and indices of the efficiency of the sediments as collectors of reactive nuclides over longer time scale. In sediment cores from Long Island Sound (marine) and Lake Whitney (fresh-water) 7Be was measurable in the top 2-3 cm. Diffusion-analog particle-mixing coefficients calculated from these data are in the range of 10-7 cm2/s. For Long Island Sound the coefficients are lower by factors of 3-6 than those estimated from the depth distributions of excess 234Th at the same stations [14]. For Lake Whitney the calculated mixing coefficient is an upper limit because of the possibility of a sampling artifact. Measurements of total (wet + dry) atmospheric deposition of 7Be in New Haven give an average flux of 0.07 dpm/cm2 day during March-November, 1977; this is equivalent to a steady-state inventory of 5.4 dpm/cm2 in a perfect collector. Sediment cores from Long Island Sound contain about half this 7Be inventory, consistent with either a mean residence time for 7Be in the water column of about one half-life or with post-depositional loss of 7Be from Long Island Sound sediments. The Lake Whitney cores contain about 5 dpm/cm2, much nearer the atmospheric delivery. A higher inventory of 7Be in fresh-water, as compared to marine, sediments could be due either to a shorter mean residence time for 7Be in fresh water or to lateral transport processes in the lake or its catchment. High inventories of excess 210Pb and 239,240Pu in Lake Whitney sediments demonstrate the importance of lateral transport on longer time scales at least. Department of Earth and Planetary Science, Massachusetts Institute of Technology, Cambridge, MA 02139, U.S.A.
Concentrations of *Be, *ZrNb, øRu, and mC'e were determined in surface water and ver- tical profiles in the North Pacific Ocean. Latitudinal distribution of radionuclides in equatorial waters differed from previous patterns of both terrestrial and oceanic fallout of long-lœved fission products. Fallout rates were quite uniform across narrow latitude belts, with co.nstant amounts of radionuclides occurring both vertically and horizontally in the water mass. The short-lived radionuclides were uniformly distributed in the mixed layer, but decreased in concentration as the thermocline was penetrated. Vertical eddy diffusion coefficients, calcu- lated fromBe and *52rNb data., were 0.5-0.7 cm'/see within the upper boundary of the main oceanic thermocline. Direct measurement of fallout deftvery to the surfaces of the world's oceans is very difficult as evidenced by the fact that various approaches for its estimation have led to different values. Volchok and Krey (1967) concluded that the total deposition of *øSr was the same on both land and ocean surfaces, based on material balance between the amount of "Sr introduced by weapons testing and that measured in the atmosphere and deposited on land surfaces. An earlier pubftcation by Volchok (1966b) proposed that oceanic fallout averaged 50% higher than fallout over land surfaces, a value used by Broecker (1966) for testing his box model of oceanic mixing. Measurements of *øSr concentra- tions in shallow water off the Bahama banks 3-4 times those observed over land, and that reductions in concentration require much more rapid mixing within the thermocftne than that projected by Broecker. These delivery estimates of fallout isotopes to the ocean surface are based on incremental changes in concentrations of the long-lived fis- sion products with time, or are impfted from their distributions with depth, and have resulted in divergent estimates of both the absolute magnitude of oceanic fallout and mixing rates
The concentrations of 7Be and other radionuclides were
measured in air, rain, and seawater in a region east of Barbados,
British West Indies, in the summers of 1968 and 1969 during the Barbados
Oceanographic and Meteorological Experiment. The radionuclide
inventories in the sea varied rapidly owing to the horizontal motion of
seawater through the sampling region. The salinity also varied
considerably, presumably as a result of Amazon River water carried into
the sampling region by the Guiana current, which flows northwestward
along the coast of South America. The 103Ru to
95Zr ratio in the top 15 m of the sea indicated that large
amounts of these radionuclides from the French nuclear test series at
23°S beginning July 7, 1968, were transported into the sampling
region, probably by the Guiana current, on August 15, 1968, and also in
June but not in May of 1969. The deposition Of 7Be on the sea
surface by rainfall in the sampling region in August 1968 and May
through July 1969 was only 13 and 26%, respectively, of that necessary
to maintain the measured inventories. it is possible, however, that the
inventories resulted from wet deposition outside the sampling region,
such as in the intertropical convergence zone, followed by advective
transport of the water into the sampling region. The calculated average
deposition velocity Of 7Be was 1.0 cm/s, and the calculated
average yearly 7Be flux across the sea surface was
1.6×10-2 atom cm-2 s-1. The
calculated vertical eddy diffusion coefficient in the sea decreased from
greater than 7 cm2/s at the surface to 0.25-0.85
cm2/s at 30-40 m.
Samples of atmospheric particulate matter and total atmospheric deposition were collected for a one-year period at a rural site on the Washington coast. Samples were analyzed for 13 stable elements and 7Be. The ratios of elements to 7Be in air and total deposition samples were similar. The total deposition rates of elements measured were used to predict total deposition velocities of those elements in other areas, then compared to actual measurements at those locations.
A sampler which permits concentration of both particulate and dissolved radionuclides from large volumes of ocean and freshwater has been developed and tested. The water sample passes through a filtration section for particle removal, then through a sorption section where the radionuclides of interest are removed on sorption or ion exchange beds. Components of the sampler which contact the water are of polyvinyl chloride construction, and flow rates of about 40 l./min are employed. This sampler has been successfully employed in concentrating some twenty radionuclides from ocean and fresh waters.
Analyses of suspended particulate matter have been carried out on samples from different depths between 0 and 4000m, in the northeast Atlantic. The total mass of suspended matter, particulate organic carbon, silicon, iron, aluminum, phosphorus, were determined. In surface waters (0–150 m), the average concentration in particulate matter (mass per vol.) is 3·8 higher than between 150 and 4000m. For carbon the ratio is 4·5 and for phosphorus 10·8. On the other hand, silicon, aluminium and iron are often as abundant in deep water as in the surface layer.RésuméDes analyses le particules en suspension ont été faites à partir d'échantillons prélevés à diverses profondeurs entre 0 et 4000 m, dans l'Atlantique nord-est. Le poids de particules, les teneurs en carbone organique, silicium, fer, aluminium, phosphore ont été déterminés. Dans la zone superficielle (0–150 m), la concentration moyenne des particules (en masse par vol.) est 3,8 fois plus importante q'entre 150 et 4000 m. Pour le carbone, le rapport est 4,5 et pour le phosphore il est de 10,8. Par contre le silicium, l'aluminium et le fer souvent aussi abondantsdans la zone profonde que dans la zone superficielle.
On the use of cosmogenic radionuclides of beryllium for ocean transport studies
- Gosink
Gosink, T.A., 1976. On the use of cosmogenic radionuelides of beryllium for ocean transport studies. Mar. Sci. Commun., 2: 413--417.
Reply to comment by W
- T A Gosink
Gosink, T.A., 1977. Reply to comment by W.B. Silker. Mar. Sci. Commun., 3:277--278.
Adsorption of hydrolysable metals at the oxide--water interface: I. Adsorption of cobalt(II) on TiO 2 and SiO 2 as model systems
- R James
- T Healy
James, R. and Healy, T., 1972. Adsorption of hydrolysable metals at the oxide--water interface: I. Adsorption of cobalt(II) on TiO 2 and SiO 2 as model systems. J. Colloid Interface Sci., Vol. 40, pp. 42--68.
Comment on 'Probable error in the use of cosmogenic radio-nuclides of beryllium for ocean transport studies A sampler for concentrating radio-nuclides from natural waters
- W B Silker
Silker, W.B., 1977. Comment on 'Probable error in the use of cosmogenic radio-nuclides of beryllium for ocean transport studies', by T.A. Gosink. Mar. Sci. Commun., 3: 275. Silker, W.B., Perkins, R.W. and Rieck, H.G., 1971. A sampler for concentrating radio-nuclides from natural waters. Ocean Eng., 2: 49--55.
Reply to comment by W.B. Silker
- Gosink
Comment on ‘Probable error in the use of cosmogenic radio-nuclides of beryllium for ocean transport studies’, by T.A. Gosink
- Silker